Or scrap that Nationwide deal and just let people into the Town End for £15
This. The Town End was at it's absolute peak (in my living memory) in the early 2000's when there were no season tickets and you just turned up with a crispy ten. Would work out about £14/£15 with inflation I should think. People think £4 isn't a lot, but it's all about making people break another note and put them off.